Hyperopia or longsightedness is a condition in which the optical components of the eye are not strong enough, and so light is not focussed onto the retina. This results in blurred vision that is usually worse at shorter distances.
A little hyperopia is not a problem because the lens compensates easily but if there is a significant amount of hyperopia, the effort of focusing (called accommodation) can lead to symptoms.
Hyperopic people may get tired eyes or headaches after a lot of visual work, even if their vision is clear. Reading is more difficult and school work can be affected. Because a hyperopic person often can see well in the distance, a letter chart test alone may miss hyperopia.